Snap action switch mechanism



1964 G. R. SHEPHERD ETAL 3,154,648

SNAP ACTION SWITCH MECHANISM Filed Aug. 16, 1962 United States Patent Filed Aug. 16, 1962, Ser. No. 217,397 Claims priority, application Great Britain, June 21, 1%2, 23,898/62 3 Claims. (Cl. 200-67) This invention relates to electric switches and more especially, but not solely, "for use in energy regulators.

The invention consists in an electric switch comprising a contact, toggle means for deflecting the contact, movable means comprising a second contact for co-operating with the first and a back stop to limit the movement of the first contact away from the second.

This arrangement has considerable flexibility. Thus, When the contacts are closed the position of adjustment of the movable means will determine the position in which an independent toggle switch actuator will snap the toggle means over to the other extreme position in which the contacts are open. Also the back stop will fix this other position.

By a more extensive movement of the movable means the toggle means can actually be switched to the con tact open position independently of the position of the toggle switch actuator.

The back stop may be replaced if desired by a further contact.

The invention will be further described with reference to the accompanying drawings.

FIGURE 1 is a side elevation of a switch according to the invention in the closed position.

FIGURE 2 is a similar view showing the open position.

FIGURE 3 is an underneath View; and

FIGURE 4 is a plan view.

As shown, the switch comprises a toggle switch mechanism, the principal element of which is here shown as comprising a beryllium-copper alloy stamped strip 1, the shape of which is apparent from FIGURE 4. It is of generally rectangular shape with rounded corners at one end, the other end being an arc of a circle. The center part is cut away to form two tongues, a long one 1a projecting from the square end and a short one lb projecting from the circular end.

The tongue 1a is formed with a window laa and two strengthening longitudinal pressed ribs lab.

The ends of both tongues are formed with transverse V-shaped stiffening and retaining lugs, 1a; 1b respectively, engaged in slots in, and thereby to support, a compression spring 2 pivotally therebetween and giving the self-restoring strip 1, snap-action operation in response to downward pressure on the member A, generally applied by means of a bimetallic strip M in the case of an energy regulator.

The circular end of strip 1 carries a contact 1c and the square end is secured to a base 3 by a screw 4 passing through an angular member 5 which constitutes a terminal.

Also secured to the base 3 to lie underneath strip 1 is a resilient strip 6 shown in FIGURES 1, 2 and 3. This comprises a hinge portion 6a adjacent the base 3 and forming a terminal, a stiiiened portion 611 bent away from strip 1, a short central portion 60 parallel to strip 1 carrying an insulating button 7 which can be pressed in upwardly by a member B, a resilient portion 6d bent up towards strip 1 and an end portion 62 carrying a contact 6 and an insulating back stop 8.

A central tongue 6e is formed in the end portion 6e so that this end can he slipped through a slot in the backstop 8 and bent down to retain it (FIGS. 1 and 2).

The backs-top extends to beyond the end of strip 1 and is provided with extensions 8a which limit the -move ment of strip 1 away from the contact of. Also attached to another portion of the base 3 is a resilient contact member constituted by a spring 9 and a cooperating backstop 10.

In operation, for a given position of the button 7, downward presure by any suitable operating member A when the switch is in position of FIGURE 1 bends the tongue 1a about the edge of member 5 giving an overcenter snap action for the switch to pass to the position shown in FIGURE 2 opening the contacts 10 and 6 The position at which this switchover occurs will clearly depend on the position of button 7, which can be adjusted by any suitable means such as member B.

The restoration movement, when pressure by the operating member A is released, is against a relatively weaker resistance since the fulcrum position of strip 1 for upward movement gives a longer effective arm.

The difference in stiffness for upward and downward movemnets is used to assist in obtaining an acceptable ratio of opearting times for closed periods and for open periods.

Pressure on button 7 when the switch is in the closed position by any operating member indicated generally at B (FIGURE 1) will also operate the switch into the open position (FIGURE 2).

Thus, extreme positions of button 7 can give permanent open and permanent closed positions of the switch.

The shape and stiiiening of parts 6a and 6b of spring 6 ensures that the adjustment of position of button 7 produces a reasonably linear positioning of contact 6f.

The resilient portion 6d improves the contact pressure at the moment of make. Thus the pressure of the contacts 6 and 10 together causes the portion 6a to give way slightly and in doing so increases the angle at which the spring 2 lies. This increase of angle increases the component force from the spring 2 to force the contacts together.

At the same time a similar reaction exerts itself on the switch operating blade 1. The window laa in this operating blade lowers the stiffness rate of the blade. Thus the reaction from the compression spring lifts the operating blade 1 resulting in an increase in angle of the compression spring 2 in relation thereto immediately after the contacts have made circuit. The overall effect is to produce a high making pressure at the contacts, and reliable over center action.

The deflection of the resilient portion 6d of the flexible member carrying the contact 6] has another useful object: it produces a slight sliding motion between the contacts, and this is of great value in rubbing away surface contamination on the contacts.

A further feature is that whenever the button 7 is changed in position, and especially when switching from a controlling position to open and also from open to a controlling position, a considerable amount of sliding action takes place at the contacts, this sliding action being associated with the arcuate positioning movements of the contacts. This sliding action effectively reduces any slight surface roughness which may be building up, Well before a tendency to weld at high points occurs.

A further useful feature of the method of adjustment shown is that for various operating positions the contacts touch at different positions on their surfaces. This assists in lengthening life by distributing the contact wear.

The circuit controlled by spring 9 is normally closed,

e.g. to operate a pilot light for all positions in which contacts 10 and of can be opened by downward pressure by suitable operating member A. When, however, button '7 rises to give the permanently open position spring 9 remains in the open position as shown in FIG- URE 2.

We claim:

1. An electric switch comprising an insulating base, a first terminal member mounted on said base, a first resiliently flexible member mounted at one end on said base in electrical connection with said first terminal member, a first contact mounted on said first resiliently flexible member at its other end, a self-restoring snap-action mechanism mounted on said first resiliently flexible member for deflecting it, means for directly engaging and operating said snap-action mechanism whereby to deflect said first resiliently flexible member, .a second terrninal member mounted on said base so as to be insulated from said first resiliently flexible member, a second resiliently flexible member mounted on said base in electrical connection with said second terminal member, a second contact mounted on said second resiliently flexible member for engagement with said first contact when said first resiliently flexible member is in its undeflected position, said second resiliently flexible member comprising a flexible length carrying said second contact and a further stifi'ened length adjacent its mounted end, a backstop mounted on said second resiliently flexible member to limit the movement of said first contact away from said second contact and means operative adjacent the junction of said flexible and stiffened lengths by which said second resiliently flexible member may be actuated over a range of movement sufiicient to operate said snap-action mechansim mounted on said first resiliently flexible member whereby to move said first resiliently flexible member into its deflected position.

2. An electric switch as claimed in claim 1 in which said second resiliently flexible member is of shallow V-shape, one arm of the V constituting said flexible length and the other arm constituting said stiffened length.

3. An electric switch as claimed in claim 1 comprising a resilient contact member mounted on said base for engagement with said second contact, a stop mounted on said base and limiting said movement of said resilient contact member whereby said resilient contact member engages said second contact on said second resiliently flexible member in its unactuated position but not in its actuated position.

References Cited in the file of this patent UNITED STATES PATENTS 1,983,076 Getchell Dec. 4, 1934 2,692,317 BletZ Oct. 19, 1954 2,821,588 Fisher Ian. 28, 1958 FOREIGN PATENTS 566,762 Great Britain Jan. 12, 1945 

1. AN ELECTRIC SWITCH COMPRISING AN INSULATING BASE, A FIRST TERMINAL MEMBER MOUNTED ON SAID BASE, A FIRST RESILIENTLY FLEXIBLE MEMBER MOUNTED AT ONE END ON SAID BASE IN ELECTRICAL CONNECTION WITH SAID FIRST TERMINAL MEMBER, A FIRST CONTACT MOUNTED ON SAID FIRST RESILIENTLY FLEXIBLE MEMBER AT ITS OTHER END, A SELF-RESTORING SNAP-ACTION MECHANISM MOUNTED ON SAID FIRST RESILIENTLY FLEXIBLE MEMBER FOR DEFLECTING IT, MEANS FOR DIRECTLY ENGAGING AND OPERATING SAID SNAP-ACTION MECHANISM WHEREBY TO DEFLECT SAID FIRST RESILIENTLY FLEXIBLE MEMBER, A SECOND TERMINAL MEMBER MOUNTED ON SAID BASE SO AS TO BE INSULATED FROM SAID FIRST RESILIENTLY FLEXIBLE MEMBER, A SECOND RESILIENTLY FLEXIBLE MEMBER MOUNTED ON SAID BASE IN ELECTRICAL CONNECTION WITH SAID SECOND TERMINAL MEMBER, A SECOND CONTACT MOUNTED ON SAID SECOND RESILIENTLY FLEXIBLE MEMBER FOR ENGAGEMENT WITH SAID FIRST CONTACT WHEN SAID FIRST RESILIENTLY FLEXIBLE MEMBER IS IN ITS UNDEFLECTED POSITION, SAID SECOND RESILIENTLY FLEXIBLE MEMBER COMPRISING A FLEXIBLE LENGTH CARRYING SAID SECOND CONTACT AND A FURTHER STIFFENED LENGTH ADJACENT ITS MOUNTED END, A BACKSTOP MOUNTED ON SAID SECOND RESILIENTLY FLEXIBLE MEMBER TO LIMIT THE MOVEMENT OF SAID FIRST CONTACT AWAY FROM SAID SECOND CONTACT AND MEANS OPERATIVE ADJACENT THE JUNCTION OF SAID FLEXIBLE AND STIFFENED LENGTHS BY WHICH SAID SECOND RESILIENTLY FLEXIBLE MEMBER MAY BE ACTUATED OVER A RANGE OF MOVEMENT SUFFICIENT TO OPERATE SAID SNAP-ACTION MECHANISM MOUNTED ON SAID FIRST RESILIENTLY FLEXIBLE MEMBER WHEREBY TO MOVE SAID FIRST RESILIENTLY FLEXIBLE MEMBER INTO ITS DEFLECTED POSITION. 